U.S. patent number 4,914,949 [Application Number 07/266,229] was granted by the patent office on 1990-04-10 for torsional vibration damper.
This patent grant is currently assigned to Firma Carl Freudenberg. Invention is credited to Rainer Andra, Werner Bauer, Friedrich Reinhold, Georg Schafer, Gunter Ullrich.
United States Patent |
4,914,949 |
Andra , et al. |
April 10, 1990 |
Torsional vibration damper
Abstract
A torsional vibration damper in which the hub ring and the
flyring are interconnected through vulcanized-in basic resilient
elements as well as resilient units made of rubber that are
uniformly distributed around the circumference. These consist of
columnar first and second resilient elements which at their outer
surfaces merge into one another and at their inner surfaces are
spaced from one another. The second resilient elements are
precompressed by the first resilient elements and, when the
torsional vibration damper is not rotating, are spaced at their
outer surfaces from the inner surface of the flyring. At a desired
speed of rotation, they are caused by centrifugal force to bear
immovably on the inner surface of the flyring. This mechanical
connection places their spring action in parallel with the spring
action of the basic resilient elements.
Inventors: |
Andra; Rainer (Limburg,
DE), Ullrich; Gunter (Hemsbach, DE), Bauer;
Werner (Weinheim, DE), Reinhold; Friedrich
(Heddesheim, DE), Schafer; Georg (Weinheim,
DE) |
Assignee: |
Firma Carl Freudenberg
(Weinheim, DE)
|
Family
ID: |
27194915 |
Appl.
No.: |
07/266,229 |
Filed: |
October 28, 1988 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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55602 |
May 29, 1987 |
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Foreign Application Priority Data
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Oct 1, 1986 [DE] |
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3633414 |
Nov 8, 1986 [DE] |
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363820 |
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Current U.S.
Class: |
74/574.4; 464/87;
464/89 |
Current CPC
Class: |
F16F
15/1202 (20130101); F16F 15/1435 (20130101); F16F
15/1442 (20130101); Y10T 74/2131 (20150115) |
Current International
Class: |
F16F
15/10 (20060101); F16F 15/14 (20060101); F16F
015/10 () |
Field of
Search: |
;74/572,573R,573F,574
;464/89,87,90 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2311985 |
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Sep 1974 |
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DE |
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2831076 |
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Jan 1980 |
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DE |
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3535803 |
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Sep 1986 |
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DE |
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631528 |
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Aug 1982 |
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CH |
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1597760 |
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Sep 1981 |
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GB |
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Other References
Rules of Practice, Jan. 1970, 37CRF, p. 139, Symbols for
Draftsmen..
|
Primary Examiner: Luong; Vinh
Attorney, Agent or Firm: Felfe & Lynch
Parent Case Text
This application is a continuation of application Ser. No. 055,602,
filed May 29, 1987 now abandoned.
Claims
What is claimed is:
1. In a torsional vibration damper comprising a hub ring and a
flyring which are interconnected through basic resilient elements
that are uniformly distributed around the circumference and are
capable of angular displacement relative to each other, and further
comprising first resilient elements and second resilient elements
which are fastened to the hub ring mechanically in parallel with
the basic resilient elements and which are spaced at their outer
surfaces from the inner surface of the flyring by an air gap when
the device is not rotating and are adapted to be cause by the
centrifugal force generated at a desired rotational speed to bear
immovably against the flyring, the first and second resilient
elements being integrally joined together at their outer
extremities to form a unit and consisting of vulcanized-in rubber
bodies, the improvement wherein the first and second resilient
elements are columnar in shape; wherein at least one first
resilient element is associated with each second resilient element
on both sides thereof in the circumferential direction; and wherein
the first and second resilient elements of every resilient unit so
formed are circumferentially spaced from one another at their inner
extremities.
2. A torsional vibration damper according to claim 1, wherein the
total cross-sectional area of the first resilient elements of each
resilient unit and the cross-sectional area of the associated
second resilient element are substantially equal.
3. A torsional vibration damper according to claim 1, wherein the
first and second resilient elements are joined together in a region
whose cross-sectional area is substantially equal to the sum of the
cross-sectional areas of the first and second resilient
elements.
4. A torsional vibration damper according to claim 1, wherein the
circumferential spacing of the first and second resilient elements
of each resilient unit is such that the imaginary extensions of
their respective axes intersect at an angle of from 25 to 65
degrees.
5. A torsional vibration damper according to claim 4, wherein the
angles obtained on the two sides of each resilient unit have
differing values.
6. A torsional vibration damper according to claim 1, wherein an
auxiliary mass is incorporated into the second resilient element.
Description
BACKGROUND OF THE INVENTION
The invention relates to a torsional vibration damper comprising a
hub ring and a flyring which are capable of angular displacement
relative to each other. The hub ring and flyring are connected
together by basic resilient elements that are uniformly distributed
around the circumference as well as by first and second resilient
elements which are vulcanized to the hub ring, parallel to the
basic resilient elements, and which are spaced at their outer
surfaces from the inner surface of the flyring when the device is
not rotating. These first and second resilient elements are adapted
to be caused by the centrifugal force, generated at the desired
rotational speed, to bear immovably against the flyring.
A torsional vibration damper of this type is known from German
patent No. 3,535,803 issued on Sept. 11, 1986. The wear sustained
by the opposed circumferential surfaces of the second resilient
elements and the flyring, respectively, even after short-term use,
is less than satisfactory.
SUMMARY OF THE INVENTION
The principal objective of the present invention is to provide a
torsional vibration damper in which the wear of the opposed
circumferential surfaces of the second resilient elements and of
the flyring is greatly reduced in operation so that the service
life of the device is lengthened.
This objective is achieved, in accordance with the invention, with
a torsional vibration damper of the type described above wherein
(1) the first and second resilient elements are given a columnar
shape; (2) at least one first resilient element is associated with
each second resilient element on both sides thereof in the
peripheral direction; and (3) the first and second resilient
elements of every resilient unit so formed are circumferentially
spaced from one another at their inner surfaces.
The first and second resilient elements merge into one another at
their outer circumferences, and thus are formed or vulcanized
together. Since the first resilient elements are associated with
the radially extending second resilient elements in an inclined
manner, their absolute lengths differ. During the cooling that
follows vulcanization, this difference in length leads to tensile
stresses in the first resilient elements and to compressive
stresses in the second resilient elements. The spacing of the outer
surfaces of the first and second resilient elements from the inner
surface of the flyring is therefore maintained until a high
rotational speed is reached, thus precluding any wear during
starting. Nevertheless, good damping action is obtained, which is
largely due to the springy resilience of the basic resilient
elements and of the mass of the flyring.
When still higher speeds of rotation are reached, the first and
second resilient elements bear with their outer surfaces immovably
against the inner surface of the flyring and thus are placed
mechanically in parallel with the basic resilient elements. The
damping action so obtained is a function of resiliency of all the
resilient elements combined and of the mass of the flyring. It thus
readily meets the requirements imposed by high speeds of
rotation.
Especially in automotive applications, the torsional vibration
damper of the invention exhibits greatly reduced wear of the
opposed circumferential surfaces of the first and second resilient
elements and of the flyring, respectively, which are in contact
with one another only at high rotational speeds. It is thought that
this reduced wear is attributable mainly to the fact that, with
increasing rotational speeds, internal-combustion engines develop
very high available power, permitting critical speed ranges to be
rapidly traversed. The duration of frictional contact between the
outer surfaces of the second resilient elements and the inner
surface of the flyring is therefore limited to a minimum.
The total cross-sectional areas of the first resilient elements of
each resilient unit and the total individual cross-sectional area
of the associated second resilient element in such unit are
advantageously made substantially equal. The specific
cross-sectional loads are then largely balanced, which makes for
economical material usage.
Also advantageously, the first and second resilient elements merge
into one another in a transition zone whose cross-sectional area
substantially corresponds to the cross-sectional area of the first
resilient elements. The forces generated by the shrinkage of the
first resilient elements are then transmitted particularly well to
the second resilient elements. This is very important so far as the
functioning of the torsional vibration damper of the invention is
concerned.
The circumferential spacing of the first and second resilient
elements of each resilient unit is advantageously such that the
imaginary extensions of the respective axes intersect at an angle
of between 25 and 65 degrees. This permits the wear in sustained
operation to be reduced to a minimum. In accordance with a further
embodiment, the angles obtained on the two sides of each resilient
unit have differing values.
Such a design is especially advantageous when the torsional
vibration damper of the invention is used in the drive train of an
motor vehicle. It results in spring characteristics, and thus in
different damping characteristics, that are dependent upon the
direction of rotation of the associated shaft. Such characteristics
are frequently desirable in applications that pose problems.
For a full understanding of the present invention reference should
now be made to the following detailed description of the preferred
embodiment of the invention and to the accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWING
The single FIG. is an elevational, cross-sectional view of a
section of the torsional vibration damper according to the
preferred embodiment of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The torsional vibration damper shown in the single Figure comprises
a flyring 3 and a hub ring 4 which are connected together by basic
element 6 and intermediate resilient units that are uniformly
distributed around the circumference. Openings 7 are provided
between the basic elements 6 and these intermediate resilient
units. The intermediate resilient units are all of the same design,
each including in the center a radially extending second resilient
element 2, which is statically secured in position only on its
inner surface to the hub ring 4. The second resilient element 2 is
flanked on both sides in the circumferential direction by two first
resilient elements 1, these being oppositely inclined in the
circumferential direction. These first and second resilient
elements are integrally joined together at their outer extremities;
at their inner extremities the first and second resilient elements
are circumferentially spaced providing openings 8. The absolute
length in the direction in which the first resilient elements
extend is greater than that of the associated second resilient
element 2. The absolute value of the shrinkage following
vulcanization is therefore greater for the first resilient elements
1 than for the second resilient element 2. This results in a latent
static precompression in the second resilient element 2.
The radial spacing 9 between the outer face of the second resilient
element 2 and the inner surface of the flyring 3, as shown in the
single Figure, therefore remains nearly unchanged up to very high
speeds of rotation. This spacing largely precludes fictional wear
during starting.
At still higher speeds, the precompression is overcome by
centrifugal force, and the first and second resilient elements 1
and 2 bear with their outer surfaces on the inner surface of the
flyring 3. They are therefore placed mechanically in parallel with
the basic resilient elements 6, with their springiness being
effective in the circumferential direction. The damping
characteristics of the torsional vibration damper are thus
radically changed.
An auxiliary mass 5, which may consist of steel, for example, may
be vulcanized into the second resilient element 2 near its outer
surface. Its use is conducive to rigid coupling of the outer
surface of the second resilient element to the inner surface of the
flyring 3 at high rotational speeds. In addition, a similar
auxiliary mass may be used for the secure placement of an outwardly
directed brake lining on the second resilient element 2. However,
its use may be dispensed with in many cases and is not a central
feature of the present invention.
As shown in the Figure, the first and second resilient elements 1
and of each resilient unit are spaced such that their respective
axes intersect at angles .alpha. and .beta. respectively, of
between 25 and 65 degrees. This reduces the wear in sustained
operation to a minimum. Advantageously, angles .alpha. and .beta.
may have different values.
There has thus been shown and described a torsional vibration
damper which fulfills all the objects and advantages sought
therefor. Many changes, modifications, variations and other uses
and applications of the subject invention will, however, become
apparent to those skilled in the art after considering this
specification and the accompanying drawing which disclose the
preferred embodiment thereof. All such changes, modifications,
variations and other uses and applications which do not depart from
the spirit and scope of the invention are deemed to be covered by
the invention which is limited only by the claims which follow.
* * * * *